ARGl'I.lD.K OF THE WOODS HOLE REGION. 



L23 



Argulus catostomi Dana & Herrick. Female only known. 



Carapace large, orbicular, wider than long, almost covering the swimming legs; posterior sinus 

 broad, with its sides approximate^ parallel; antero-lateral sinuses scarcely noticeable; chitin rings in 

 tin' lateral areas very unequal in size, the larger <m<' extending forward to the sucking disks, and 

 having adeep indentation on its inner margin near the center, into which the smaller one projects. 

 Abdomen comparatively very small, orbicular, wider than long, cut less than one-third its length; 

 anal sinus narrow; papillae basal. Antenna? comparatively small ami weak; poorly armed; sucking 

 disks large, placed well forward; second maxillipeds large ami strong, every joint with a roughened 



0.5 \mm. 



Argvlui catostomi Dana & Herrick. Female, a, Dorsal surface; b, ventral surface; c, posterior inaxilliped ./, antennie. 



area on its ventral surface; basal plate with a raised pear-shaped area near its center; lobes (not teeth I 

 on its posterior edge broad and squarely truncated, usually three in number but often reduced by 

 fusion to two. Swimming legs scarcely reaching the edge of the carapace; two anterior pairs with 

 recurved flagella; lobes on the basal joints of the posterior pair medium size, hoot-shaped. Color a 

 uniform light sea-green, turning much darker in alcohol. Length, 12 mm.; length of carapace, 9.6 

 mm.; breadth of carapace, 11.2 mm.; length of abdomen, 2.3 mm.; breadth of abdomen, 2.4 nun. 

 I Description from living specimens. ) 



